The present invention relates to a process for the preparation of alpha-haloalkyl esters.
Alpha-haloalkyl esters are useful and versatile intermediates having two different reactive groups attached to one carbon atom. They can be used for the preparation of acycloxyalkyl esters by reaction with carboxylic acids or their alkali or silver salts, for example in order to obtain pharmaceuticals (cf. French Demande 2,164,489 or German Offenlegungsschrift 2,706,413). They may also be used for the preparation of alpha-acycloxy nitriles by reaction with alkali cyanides which nitriles can be used as plant protective agents (cf. German Offenlegungsschrift 2,919,974).
Alpha-haloalkyl esters may further be used for the preparation of fulvenes for example by reacting an alpha-haloalkyl ester of acetic acid with sodium cyclopentadienide followed by elimination of acetic acid (cf. Helv. Chim. Acta 54 (1971) pp. 1037-1046). Fulvenes can be applied as anti-knock compounds in fuels for combustion engines (cf. U.S. Pat. No. 2,589,969) or as components of polymer compositions (cf. U.S. Pat. No. 3,390,156).
Alpha-haloalkyl esters have hitherto been prepared by procedures such as chlorination of alkyl esters or addition of a hydrogen halide to alpha-alkenyl esters or by reacting an acyl halide with an aldehyde. The reaction last mentioned appears to be the most useful and widely used method for preparing alpha-haloalkyl esters (cf. Acta. Chem. Scand. 20 (1966) pp. 1273-1280).
It has now been found that alpha-haloalkyl esters can simply be prepared by reacting an acyl halide with hydrogen thereby avoiding the separate preparation of an aldehyde necessary in the known methods mentioned above.